Abstract: A semi-trailer having at its front end at least one landing leg (8) which may be supported in its operative position by a strut (12) which is mounted slidably and pivotally to the chassis by means of a mounting (16) and which leg(s) is(are) raisable by a power unit; the strut(s) (12) may be locked by pin or pins (22) engaging in holes (29, 52) in the strut and the pin(s) latched in at least a partially disengaged position for movement of the strut between the operative position of the leg and an inoperative position, the pin(s) being unlatched to engage in a hole (29, 52) by movement of the strut in the mounting.